TW201616577A - Etching Method and Storage Medium - Google Patents

Abstract

An etching method includes disposing a target substrate within a chamber. The target substrate has a first silicon oxide film formed on a surface of the target substrate by a chemical vapor deposition method or an atomic layer deposition method, a second silicon oxide film that includes a thermally-oxidized film and a silicon nitride film. The second silicon oxide film and the silicon nitride are formed adjacent to the first silicon oxide film. The etching method further includes supplying an HF gas and an alcohol gas or water vapor into the chamber to selectively etch the first silicon oxide film with respect to the second silicon oxide film and the silicon nitride film.

Description

Etching method

The present invention relates to an etching method for etching a tantalum oxide film or a natural oxide film of a CVD system formed on a substrate.

Recently, in the manufacturing process of a semiconductor device, a method called chemical Oxide Removal (COR) has been attracting attention as a method of refining etching which can replace plasma etching, which is chemically oxidized. The material removal treatment is performed by chemically etching without generating plasma in the chamber.

As the COR, a process is known in which a hydrogen fluoride (HF) gas and an ammonia (NH ₃ ) gas are adsorbed to a tantalum oxide film (SiO ₂ film) in a chamber maintained in a vacuum (the tantalum oxide film is present in As a surface of the semiconductor wafer of the object to be processed, and reacting with the antimony oxide film to form ammonium hexafluoroantimonate ((NH ₄ ) ₂ SiF ₆ ; AFS), in the next project, by heating The SiO ₂ film is etched in such a manner that the ammonium hexafluoroantimonate is sublimated (for example, refer to Patent Documents 1 and 2).

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-39185

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-160000

However, in the manufacturing process of the semiconductor device, the SiO ₂ film to be etched is a CVD system SiO ₂ film formed by a chemical vapor deposition method (CVD method) or an atomic layer deposition method (ALD method), but in the semiconductor In the wafer, there is a case where a thermal oxide film (the thermal oxide film is adjacent to a CVD system SiO ₂ film, a SiO ₂ film formed by thermally oxidizing Si) or a tantalum nitride film (SiN film) is adjacent to each other. A method of etching a CVD system SiO ₂ film with a high selectivity ratio with respect to a thermal oxide film or a SiN film.

Further, although the Si-based material is naturally oxidized to form a natural oxide film on the surface of the semiconductor wafer, it is desirable to have a method of etching only the thermal oxide film or the SiN film existing on the semiconductor wafer and etching only the natural oxide film. .

However, conventionally, when HF gas and NH ₃ gas are used as the etching gas, it is difficult to etch the CVD system SiO ₂ film or the natural oxide film with a sufficient selection ratio with respect to the thermal oxide film and the SiN film.

The present invention has been made in view of the circumstances, and it is an object of the present invention to provide an etching method which can be used with respect to a thermal oxide film and a SiN film by a chemical method which does not generate plasma in a chamber. High selectivity ratio to etch CVD system SiO ₂ film or natural oxide film.

In order to solve the above problems, the present invention provides an etching method characterized by having a first hafnium oxide film formed by a chemical vapor deposition method or an atomic layer deposition method on a surface thereof, and having a second hafnium oxide film ( The second yttria film is formed adjacent to the first yttria film and composed of a thermal oxide film, and the substrate to be processed of the tantalum nitride film is placed in the chamber to supply HF gas and alcohol gas to the chamber or The water vapor is used to selectively etch the first hafnium oxide film with respect to the second hafnium oxide film and the tantalum nitride film.

Moreover, the present invention provides an etching method characterized in that a substrate to be processed (the substrate to be processed has a thermal oxide film and a tantalum nitride film, and a natural oxide film is formed on the surface) is disposed in the chamber. The HF gas, the alcohol gas, or the water vapor is supplied into the chamber, whereby the natural oxide film is selectively etched and removed from the thermal oxide film and the tantalum nitride film.

In any of the above etching methods, an inert gas may be further supplied to perform an etching treatment. In this case, as the inert gas, Ar gas or N ₂ gas can be suitably used.

Further, in any of the etching methods described above, in the etching, the pressure in the chamber is set to be in the range of 66.7 to 1333.3 Pa, and the temperature of the mounting table on which the substrate to be processed is placed in the chamber is set. A range of 0 to 30 ° C is preferred.

As the alcohol gas, it can be used from ethanol (C ₂ H ₅ OH), methanol (CH ₃ OH), propanol (C ₃ H ₇ OH), butanol (C ₄ H ₉ OH). At least one of the choices.

The volume ratio of the alcohol gas or the water vapor to the total amount of the HF gas + the alcohol gas or the water vapor in the etching is preferably in the range of 3 to 50% by volume.

Moreover, the present invention provides a memory medium that operates on a computer and memorizes a program for controlling an etching apparatus. The memory medium is characterized in that the program is executed to perform any of the above etchings. The method is to let the computer control the aforementioned etching device.

According to the present invention, by supplying HF gas and alcohol gas or water vapor into the chamber, plasma is not generated in the chamber, but is extremely high with respect to the thermal oxide film and the tantalum nitride film formed on the substrate to be processed. The yttrium oxide film is formed by etching (the yttrium oxide film is formed on the surface of the substrate to be processed by chemical vapor deposition or atomic layer deposition) or the natural oxide film (the natural oxide film is formed in the processed The surface of the substrate).

1‧‧‧Processing system

2‧‧‧ Moving in and out

3‧‧‧Load lock room

5‧‧‧ etching device

6‧‧‧Control Department

11‧‧‧1st wafer transfer mechanism

17‧‧‧2nd wafer transfer mechanism

40‧‧‧ chamber

43‧‧‧ gas supply mechanism

44‧‧‧Exhaust mechanism

61‧‧‧ gas introduction nozzle

62‧‧‧Common gas supply piping

63‧‧‧N ₂ gas supply source

64‧‧‧HF gas supply source

65‧‧‧Supply source of ethanol gas

66,67,68‧‧‧ gas supply piping

W‧‧‧Semiconductor Wafer

Fig. 1 is a schematic configuration diagram showing an example of a processing system in which an etching apparatus for performing an etching method according to an embodiment of the present invention is mounted.

Fig. 2 is a cross-sectional view showing a heat treatment apparatus mounted in the processing system of Fig. 1.

Fig. 3 is a cross-sectional view showing an etching apparatus mounted in the processing system of Fig. 1.

4 is a view showing an etching amount and an etching selectivity ratio when ALD-SiO ₂ , Th-SiO _{2 ,} and ALD-SiN are etched by a conventional gas system and a gas system of the present invention in Experimental Example 1.

[Fig. 5] shows the etching property of ALD-SiO ₂ , Th-SiO ₂ and ALD-SiN in the case where the HF gas alone is used as the etching gas in Experimental Example 2 and the case where the ethanol gas is added to the HF gas. (a) is a graph showing the amount of etching; and (b) is a graph showing ALD-SiO ₂ /Th-SiO ₂ and ALD-SiO ₂ /ALD-SiN as etching selectivity ratios.

6] Fig. 6 is a graph showing the dependence of ALD-SiO ₂ , Th-SiO ₂ and ALD-SiN in Experimental Example 3 on the flow rate of ethanol gas with respect to etchability; (a) is a graph showing the amount of etching; The graph shows the ALD-SiO ₂ /Th-SiO ₂ and ALD-SiO ₂ /ALD-SiN as etching selectivity ratios.

7] FIG. 7 is a view showing etching properties of ALD-SiO ₂ , Th-SiO ₂ , ALD-SiN, and BSG in Experimental Example 4; (a) showing the relationship between etching time and etching amount; (b) The general description indicates the etching selectivity ratio of Th-SiO ₂ and ALD-SiN with respect to ALD-SiO ₂ and BSG.

Fig. 8 is a graph showing the relationship between the number of etching treatments with respect to ALD-SiN and the etching amount in Experimental Example 5.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<An example of a processing system used in an embodiment of the present invention>

Fig. 1 is a schematic block diagram showing an example of a processing system in which an etching apparatus according to an embodiment of the present invention is mounted. The processing system 1 includes a loading/unloading unit 2, and carries in and out a semiconductor wafer (hereinafter, simply referred to as a wafer) W as a substrate to be processed; and two load lock chambers (L/L) 3 are provided adjacent to each other. In the loading/unloading unit 2, the heat treatment device 4 is disposed adjacent to each of the load lock chambers 3 and heat-treated the wafer W. The etching apparatus 5 of the present embodiment is disposed adjacent to each of the heat treatment apparatuses 4, and is not in the cavity. The plasma is generated indoors, and the wafer W is etched; and the control unit 6 is formed.

The loading/unloading unit 2 includes a transfer chamber (L/M) 12 (the transfer chamber is provided with a first wafer transfer mechanism 11 that transports the wafer W therein). The first wafer transfer mechanism 11 has two transfer arms 11a and 11b that hold the wafer W slightly horizontally. In the side portion in the longitudinal direction of the transfer chamber 12, a mounting table 13 is provided, and for example, three carriers C capable of arranging a plurality of wafers W in parallel can be connected to the mounting table 13. Further, a positioner 14 is provided (the positioner is adjacent to the transfer chamber 12, and the wafer W is rotated to optically determine the amount of eccentricity to be aligned).

In the loading/unloading unit 2, the wafer W is held by the transfer arms 11a and 11b, and is moved in a straight horizontal plane by the driving of the first wafer transfer mechanism 11, and is lifted and lowered. Transfer to the desired location. Moreover, by carrying the transfer arms 11a, 11b respectively The carrier C, the positioner 14 and the load lock chamber 3 on the table 13 are moved in and out, and are carried in and out.

Each of the load lock chambers 3 is connected to the transfer chamber 12 in a state in which the gate valve 16 is interposed between the transfer chambers 12 and the transfer chambers 12, respectively. In each of the load lock chambers 3, a second wafer transfer mechanism 17 that transports the wafer W is provided. Further, the load lock chamber 3 is configured to be evacuated to a predetermined degree of vacuum.

The second wafer transfer mechanism 17 has a multi-joint arm structure and has a pickup that holds the wafer W slightly horizontally. In the second wafer transfer mechanism 17, the pickup is placed in the load lock chamber 3 in a state where the multi-joint arm is retracted, and the pickup reaches the heat treatment device 4 by extending the multi-joint arm. By further extending, the etching apparatus 5 can be reached, and the wafer W can be transferred between the load lock chamber 3, the heat treatment apparatus 4, and the etching apparatus 5.

As shown in FIG. 2, the heat treatment apparatus 4 includes a chamber 20 for evacuating, and a mounting table 23 on which the wafer W is placed, and a heater 24 is embedded in the mounting table 23, and The heater 24 heats the wafer W subjected to the etching treatment, and vaporizes and removes the etching residue existing on the wafer W. On the side of the load lock chamber 3 of the chamber 20, a carry-in/out port 20a for transporting a wafer to and from the load lock chamber 3 is provided, and the carry-in/out port 20a can be opened and closed by the gate valve 22. Further, on the side of the etching apparatus 5 of the chamber 20, a loading/unloading port 20b for transporting the wafer W to and from the etching apparatus 5 is provided, and the loading/unloading port 20b can be opened and closed by the gate valve 54. A gas supply path 25 is connected to the upper portion of the side wall of the chamber 20, and the gas supply path 25 is connected to the N ₂ gas supply source 30. Further, an exhaust path 27 is connected to the bottom wall of the chamber 20, and the exhaust path 27 is connected to the vacuum pump 33. In the gas supply path 25, provided with a flow control valve system 31, the exhaust path 27, is provided with a line pressure control valve 32, and by adjusting the way these valves, the chamber 20 reaches a predetermined pressure in the N ₂ gas The atmosphere is treated with heat. An inert gas other than the N ₂ gas such as an Ar gas may be used.

The control unit 6 includes a program controller 91 including a microprocessor (computer) that controls each component of the processing system 1. The program controller 91 is connected to a keyboard or a user interface 92, which is an input operation for an operator to manage the processing system 1, and the user interface 92 has a visual display of the operation of the processing system 1. Status monitors, etc. Further, the program controller 91 is connected to a storage unit 93 for storing various processes executed by the processing system 1 under the control of the program controller, for example, in the etching apparatus 5 to be described later. A control program such as a supply of a process gas or an exhaust gas in a chamber, or a control program for executing a predetermined process in each component of the processing system 1 in response to processing conditions, that is, a processing recipe or a various database. The recipe is an appropriate memory medium (not shown) that is stored in the memory unit 93. Further, if necessary, the arbitrary program is called from the memory unit 93 and executed by the program controller 91, whereby the desired processing of the processing system 1 is performed under the control of the program controller 91.

In the etching apparatus 5 of the present embodiment, pattern etching of a CVD system SiO ₂ film or etching of a natural oxide film is performed by HF gas, alcohol gas or the like. The specific configuration will be described in detail later.

In the processing system 1 as described above, as the wafer W, a CVD system SiO ₂ film (the CVD system SiO ₂ film formed by a CVD method or an ALD method) or a natural oxide film having an etching target is used as the wafer W. A wafer having a thermal oxide film and a SiN film adjacent thereto is placed in a carrier C and transported to the processing system 1 in a plurality of wafers W.

In the processing system 1, one of the transfer arms 11a and 11b of the first wafer transfer mechanism 11 is loaded from the carry-in/out unit 2 by the transfer arm 11a and 11b of the first wafer transfer mechanism 11 in a state where the gate valve 16 on the atmospheric side is opened. The carrier C is transported to the load lock chamber 3 and is taken up to the pickup of the second wafer transfer mechanism 17 in the lock lock chamber 3.

Thereafter, the gate valve 16 on the atmospheric side is closed and the inside of the load lock chamber 3 is evacuated, and then the gate valve 54 is opened, and the pickup is extended to the etching device 5 to transport the wafer W to the etching device 5.

Thereafter, the pickup is moved back to the load lock chamber 3, and the gate valve 54 is closed, and the etching process is performed in the etching apparatus 5 as will be described later.

After the etching process is completed, the gate valves 22 and 54 are opened, and the wafer W after the etching process is transferred to the heat treatment device 4 by the pickup of the second wafer transfer mechanism 17, and the N ₂ gas is introduced into the chamber. In the chamber 20, the wafer W on the mounting table 23 is heated by the heater 24 to heat and remove the etching residue or the like.

After the heat treatment of the heat treatment apparatus 4 is completed, the gate valve 22 is opened, and the wafer W after the etching process on the mounting table 23 is retracted to the load lock chamber 3 by the pickup of the second wafer transfer mechanism 17, and Any one of the transfer arms 11a and 11b of the first wafer transfer mechanism 11 is moved back to the carrier C. Thereby, the processing of one wafer is ended.

Further, in the case of the present embodiment, the reaction product such as COR in Patent Document 1 or 2 does not occur in the etching apparatus 5, and therefore the heat treatment apparatus 4 is not required. When the heat treatment apparatus is not used, the wafer W after the etching process is completed is evacuated to the load lock chamber 3 by the pickup of the second wafer transfer mechanism 17, and the first wafer transfer mechanism 11 is used. Any one of the transfer arms 11a and 11b may be moved back to the carrier C.

<Composition of etching device>

Next, the etching apparatus 5 of this embodiment will be described in detail.

Fig. 3 is a cross-sectional view showing the etching apparatus of the embodiment. As shown in FIG. 3, the etching apparatus includes a chamber 40 having a hermetic structure, and inside the chamber 40, a mounting table 42 on which the wafer W is placed in a slightly horizontal state is provided. Further, the etching apparatus 5 includes a gas supply mechanism 43 that supplies an etching gas to the chamber 40, and an exhaust mechanism 44 that exhausts the inside of the chamber 40.

The chamber 40 is constituted by the chamber body 51 and the lid portion 52. The chamber body 51 has a side wall portion 51a and a bottom portion 51b having a substantially cylindrical shape, and an upper portion is formed as an opening, and the opening is provided by the lid portion 52. To close. The side wall portion 51a and the lid portion 52 are sealed by a sealing member (not shown) to ensure airtightness in the chamber 40. On the top wall of the lid portion 52, a gas introduction nozzle 61 is inserted into the chamber 40 from above.

The side wall portion 51a is provided with a loading/unloading port 53 for loading and unloading the wafer W between the chambers 20 of the heat treatment device 4, and the loading/unloading port 53 can be opened and closed by the gate valve 54.

The mounting table 42 is slightly circular in plan view and is fixed to the bottom portion 51b of the chamber 40. Inside the mounting table 42, a temperature regulator 55 that adjusts the temperature of the mounting table 42 is provided. The temperature regulator 55 is provided with a pipe through which, for example, a temperature adjustment medium (for example, water) is circulated, and the stage 42 is adjusted by heat exchange with a temperature adjustment medium flowing in a pipe like this. The temperature is controlled by the temperature of the wafer W on the stage 42.

Gas supply mechanism 43, the system having: N ₂ gas supply source 63 is supplied as the inert gas of the N ₂ gas; HF gas supply source 64, supplying HF gas; and ethanol gas supply source 65 is supplied as an ethanol alcohol gases (C ₂ H ₅ OH) gas. Further, the first gas supply pipe 66 is connected to the N ₂ gas supply source 63, the second gas supply pipe 67 is connected to the HF gas supply source 64, and the third gas supply pipe 68 is connected to the ethanol gas supply source 65; The first to third gas supply pipes 66 to 68 are connected to the common gas supply pipe 62. The common gas supply pipe 62 is connected to the above-described gas introduction nozzle 61.

The first to third gas supply pipes 66 to 68 are provided with A flow controller 70 that performs a switching operation of the flow path and flow rate control. The flow controller 70 is constituted by, for example, an on-off valve and a mass flow controller.

In the gas supply mechanism 43 having the above configuration, the N ₂ gas supply source 63, the HF gas supply source 64, and the ethanol gas supply source 65 are respectively supplied, and the N ₂ gas, the HF gas, and the ethanol gas are respectively passed through the first to the third. The gas supply pipes 66 to 68 reach the common gas supply pipe 62 and are supplied into the chamber 40 via the gas introduction nozzle 61. Further, a shower plate may be provided on the upper portion of the chamber 40, and the gas may be supplied in a shower manner via the shower plate.

In the present embodiment, an example in which ethanol gas is used as the alcohol gas is used. However, the alcohol is not limited to ethanol, and other alcohols may be used. In this case, a supply source of the supplied alcohol gas is used. Instead of the ethanol gas supply source 65, it is sufficient. The alcohol is preferably a monovalent alcohol, and as the monovalent alcohol, methanol (CH ₃ OH), propanol (C ₃ H ₇ OH), butanol (C ₄ H) can be suitably used in addition to ethanol. ₉ OH), and may be used at least one of the plurality. Further, although there are two kinds of structural isomers in propanol and four kinds of structural isomers in butanol, any structural isomer may be used. The alcohol, although it is considered that the OH group contained therein contributes to etching, as the substance containing the OH group, water may be used instead of the alcohol. In this case, instead of the ethanol gas supply source 65, a water vapor supply source can be used to supply the water vapor.

N ₂ gas as an inert gas is used as a diluent gas. As the inert gas, an Ar gas may be used, and both an N ₂ gas and an Ar gas may be used. Further, as the inert gas, N ₂ gas or Ar gas is preferable, and other inert gas such as He may be used as a noble gas other than Ar. In addition, the inert gas, in addition to the diluent gas, can be used as the flushing gas in the flushing chamber 40.

The exhaust mechanism 44 has an exhaust pipe 82 connected to the exhaust port 81 (which is formed in the bottom portion 51b of the chamber 40), and has an exhaust pipe 82 provided to control the chamber 40. An internal pressure control valve (APC) 83 and a vacuum pump 84 for exhausting the interior of the chamber 40.

On the side wall of the chamber 40, two capacitive pressure gauges 86a, 86b are provided for insertion into the chamber 40 (the capacitive pressure gauge is used as a pressure gauge for measuring the pressure in the chamber 40). ). The capacitive pressure gauge 86a is formed for high pressure, and the capacitive pressure gauge 86b is formed for low pressure. A temperature sensor (not shown) that detects the temperature of the wafer W is provided in the vicinity of the wafer W placed on the mounting table 42.

Al is used as a material of various components constituting the chamber 40 and the mounting table 42 of the etching apparatus 5. The Al material constituting the chamber 40 may be pure, or may be an anodized person to the inner surface (the inner surface of the chamber body 51, etc.). On the other hand, since the surface of Al constituting the mounting table 42 is required to have abrasion resistance, it is preferable to perform anodizing treatment to form an oxide film (Al ₂ O ₃ ) having high abrasion resistance on the surface.

<etching method of etching device>

Next, an etching method performed by the etching apparatus configured as described above will be described.

In the present embodiment, in the state in which the gate valve 54 is opened, the above-described configuration, that is, the CVD system SiO which is the object of etching, is formed on the surface by the pickup of the second wafer transfer mechanism 17 in the lock chamber 3. wafer W ₂ film, and adjacent thereto and having a thermal oxide film and SiN film or a natural oxide film formed on the etching target, and having a thermal oxide film and SiN film on the surface of the wafer W, the transport outlet 53 from the loading It is carried into the chamber 40 and placed on the mounting table 42. The CVD system SiO ₂ film to be etched is exemplified by a film formed by an ALD method using a decane-based gas such as SiH ₄ or an amino decane or an oxidizing agent as an Si precursor, or a decane-based gas and an oxidizing agent. A boron-based gas, and a BSG film formed by a CVD method. Of course, it can also be applied to those formed by using other Si precursors. Further, examples of the SiN film include a film formed by a CVD method or an ALD method, and examples of the Si precursor include dichlorosilane (DCS; SiCl ₂ H ₂ ) and hexachlorodioxane (HCD; Si ₂ Cl). ₆ ) Wait.

Thereafter, the pickup is moved back to the load lock chamber 3, and the gate valve 54 is closed to bring the inside of the chamber 40 into a sealed state.

Next, as needed, the HF gas, the alcohol gas as the alcohol gas, and the introduction into the chamber 40 by the N ₂ gas as an inert gas, thereby selectively etching the CVD system SiO ₂ film of the wafer W or Natural oxide film.

Specifically, the temperature of the mounting table 42 is adjusted to a predetermined range by the temperature regulator 55, the pressure in the chamber 40 is adjusted to a predetermined range, and the N ₂ gas supply source 63, HF from the gas supply mechanism 43, respectively. The gas supply source 64 and the ethanol gas supply source 65 introduce the N ₂ gas, the HF gas, and the ethanol gas into the chamber through the first to third gas supply pipes 66 to 68, the common gas supply pipe 62, and the gas introduction nozzle 61, respectively. Within 40, etching of the CVD system SiO ₂ film or the natural oxide film is performed.

In this case, as described above, other alcohol gas may be used instead of the ethanol gas, and as the alcohol, a monovalent alcohol is preferable, and as the monovalent alcohol, methanol or propanol may be appropriately used in addition to ethanol. Butanol. Further, water vapor may be used instead of the alcohol gas.

The CVD system SiO ₂ film and the natural oxide film have etching characteristics different from those of the thermal oxide film or the SiN film. In other words, in the case where the HF gas, the alcohol gas, or the water vapor is appropriately diluted by an inert gas as required in the present embodiment, the SiO ₂ film and the natural oxidation are used in the CVD system. In the film, etching proceeds easily due to the OH group in the alcohol gas or the water vapor. On the other hand, in the case of the thermal oxide film or the SiN film, the OH group hardly contributes to the etching. Therefore, the CVD system SiO ₂ film and the natural oxide film can be etched at a very high selectivity with respect to the thermal oxide film or the SiN film.

The pressure in the chamber 40 of the etching treatment is preferably in the range of 66.7 to 1333.3 Pa (0.5 to 10 Torr), and the temperature of the mounting table 42 (the temperature of the wafer) is preferably 0 to 30 ° C. Good system, the pressure range is 133.3~666.7Pa (1.0~5.0Torr), the temperature of the mounting table The circumference is 0~15°C. The best system, the pressure range is 266.6 ~ 533.3Pa (2.0 ~ 4.0Torr), the temperature range of the mounting table is 0 ~ 10 °C.

As described above, the alcohol gas and the water vapor tend to increase the etching selectivity of the CVD system SiO ₂ film or the natural oxide film with respect to the thermal oxide film and the SiN film, and the alcohol gas (or water vapor) is relative to the HF gas + The volume ratio (flow ratio) of the total amount of the alcohol gas (or water vapor) is preferably in the range of 3 to 50% by volume, more preferably in the range of 5 to 15%. Further, an inert gas such as N ₂ gas preferably contains a CVD system SiO ₂ film or a natural oxide film at a high selectivity, and the inert gas is inert with respect to HF gas + alcohol gas or water vapor at this time. The volume ratio (flow ratio) of the total amount of the gas is preferably in the range of 80% by volume or less, and more preferably in the range of 55 to 75%.

In this manner, the CVD system SiO ₂ film or the natural oxide film can be etched at a high selectivity with respect to the thermal oxide film or the SiN film by using an HF gas, an alcohol gas, and an inert gas as needed. Further, by optimizing the conditions of the gas composition, pressure, temperature, and the like, it is 50 or more or more with respect to the thermal oxide film, and an extremely high etching selectivity ratio of 50 or more with respect to the SiN film. The CVD system SiO ₂ film or natural oxide film is etched. Further, on the occasion of the etching system CVD SiO ₂ film, the surface of the wafer W in the case where a natural oxide film, thermal oxide film system relative to the SiN film at a high selection ratio of etching the CVD film ₂ system SiO, at the same time , to remove the natural oxide film with a high selection ratio.

In this way, after the etching process of the etching apparatus 5 is completed, the gate valve 54 is opened and picked up by the second wafer transfer mechanism 17 The wafer W after the etching process on the mounting table 42 is carried out from the chamber 40, and the etching of the etching device 5 is completed.

<Experimental example>

Next, an experimental example will be described.

[Experimental Example 1]

Here, in the case where a conventional HF/NH ₃ -based gas is used as the processing gas and the HF/ethanol-based gas of the present invention is used as the processing gas, the etching property is compared.

As a conventional gas system, the use of the NH ₃ gas with respect to the total amount of HF gas and NH ₃ gas of a volume ratio provided into a volume% of 56.6%, N ₂ gas + Ar gas is set to become 500 ~ 1000sccm, the total gas flow is provided It is a gas of 1000 to 2000 sccm, and the temperature of the stage is set to 100 to 150 ° C, and the pressure in the chamber is set to 2 to 4 Torr. The SiO ₂ film (ALD-SiO ₂ ) and the thermal oxide film (Th formed by the ALD method) are used. -SiO ₂ ) is etched. On the other hand, as the gas system of the present invention, the volume ratio of the ethanol gas to the total amount of the HF gas and the ethanol gas (Et-OH) is set to be 10.7% by volume and N ₂ gas + Ar gas is used. 500~1500sccm, the total gas flow rate is set to 1000~2000sccm gas, and the temperature of the mounting table is set to 0~10 °C, the pressure in the chamber is set to 2~4 Torr, to ALD-SiO ₂ , Th-SiO ₂ and by ALD method The formed SiN film (ALD-SiN) is etched.

In Fig. 4, the etching amount (EA) and the etching selection ratio (Sel) at this time are shown. As shown in the figure, when a conventional HF/NH ₃ -based gas is used, ALD-SiO ₂ is etched with a high etching amount, but the etching amount of Th-SiO ₂ is also high, and relative to ALD- The etching selectivity ratio of SiO ₂ to Th-SiO ₂ (ALD-SiO ₂ /Th-SiO ₂ ) is a low value of 1.95. In this case, in the case of using the HF/Et-OH-based gas of the present invention, the etching amount of ALD-SiO ₂ is slightly inferior to the case of using the HF/NH ₃ -based gas, but Th-SiO ₂ and ALD- The etching amount of SiN is extremely small, and ALD-SiO ₂ /Th-SiO ₂ is more than 100 (112.85), and the etching selectivity ratio (ALD-SiO ₂ /ALD-SiN) of ALD-SiN with respect to ALD-SiO ₂ is The system is over 50 (57.26).

[Experimental Example 2]

Here, the effectiveness of the ethanol gas on the etching was confirmed.

When HF gas is used alone (the HF gas is set to 500 to 1000 sccm) as the etching gas, the ALD is compared with the case where the ethanol gas is added at a volume % of 4.6% with respect to the total amount of the HF gas. Etching properties of -SiO ₂ , Th-SiO ₂ and ALD-SiN. Further, the stage temperature is set to 0 to 10 ° C, and the chamber pressure is set to 0.5 to 1.0 Torr.

In Fig. 5(a), the etching amount at this time is shown; in Fig. 5(b), the etching selection ratio at this time is shown. As shown in FIG. 5, it was confirmed that when HF gas was used alone and when ethanol gas was added, the etching amount of Th-SiO ₂ and ALD-SiN did not change much, whereas ALD-SiO _{2 was used} . The amount of etching was sharply increased by the addition of the ethanol gas, and the etching selectivity was increased by adding the ethanol gas to the HF gas, and both ALD-SiO ₂ /Th-SiO ₂ and ALD-SiO ₂ /ALD-SiN significantly increased.

[Experimental Example 3]

Here, the flow rate dependence of the ethanol gas on the etching was confirmed.

The ratio of the flow rate of the ethanol gas (the flow rate of the total flow rate of the ethanol gas to the HF gas + the ethanol gas) is changed between 5 and 12%, and the ALD-SiO ₂ , Th-SiO ₂ and ALD-SiN are determined. Etchability. Further, the stage temperature is set to 0 to 10 ° C, and the chamber pressure is set to 2.0 to 3.0 Torr.

In Fig. 6(a), the etching amount at this time is shown; in Fig. 6(b), the etching selection ratio at this time is shown. As shown in Fig. 6, it was confirmed that the etching amount of ALD-SiO ₂ was high in the range of the flow rate of the ethanol gas of 5 to 12%, and the etching amount of Th-SiO ₂ and ALD-SiN was low. The tendency is that ALD-SiO ₂ /Th-SiO ₂ and ALD-SiO ₂ /ALD-SiN are very high in terms of etching selectivity. Specifically, in the range where the flow ratio of the ethanol gas is 5 to 12%, the ALD-SiO ₂ /Th-SiO ₂ tends to decrease as the flow ratio of the ethanol gas increases, but the value exceeds 100, and on the other hand, ALD-SiO ₂ /ALD-SiN, which is approximately flat for a flow ratio of ethanol gas, is a value near 50.

[Experimental Example 4]

Here, in addition to ALD-SiO ₂ , Th-SiO _{2 ,} and ALD-SiN, the etching property was confirmed for the BSG which is a SiO ₂ film formed by the CVD method.

The flow ratio of the ethanol gas to the total amount of the HF gas and the ethanol gas is set to 4.6% by volume, the total gas flow rate is set to 500 to 1000 sccm, the stage temperature is set to 0 to 15 ° C, and the chamber pressure is set to 0.5. ~1.0 Torr, and etching is performed by changing the etching time.

In Fig. 7(a), the relationship between the etching time and the etching amount of each film at this time is shown; in Fig. 7(b), the total is shown as Th-SiO ₂ and ALD-SiN with respect to ALD-SiO ₂ and BSG. Etching selection ratio. Further, the initial film thickness of the BSG was 60 nm, and when the etching amount exceeded 60 nm, the measurement could not be performed. As shown in Fig. 7(a), Th-SiO ₂ and ALD-SiN are hardly etched even if the etching time is increased. In contrast, ALD-SiO ₂ and BSG are etched as the etching time increases. The amount was increased, and as shown in Fig. 7(b), it was confirmed that both ALD-SiO ₂ and BSG had extremely high etching selectivity with respect to Th-SiO ₂ and ALD-SiN.

[Experimental Example 5]

Here, the etching property of the natural oxide film on the surface of the SiN film was confirmed.

As the etching gas, the ratio of the ethanol gas to the total amount of the HF gas and the ethanol gas is set to 16.7% by volume, and the total flow rate of the N ₂ gas + Ar gas is set to 500 to 1500 sccm, and the total gas flow rate is set to be The gas of 1000 to 2000 sccm was repeatedly subjected to etching treatment for the ALD-SiN under the following conditions: the stage temperature: 0 to 15 ° C, the chamber pressure: 2.0 to 4.0 Torr, and the etching time of 65 sec.

In Fig. 8, the relationship between the number of processes at this time and the amount of etching is shown. As shown in the figure, the first etching amount is 0.23 nm, whereas the second time and thereafter, the low value is maintained at 0.14 to 0.15 nm. This is considered to be because the natural oxide film of Si existing on the surface of the ALD-SiN has been removed in the first etching treatment. This result indicates that the natural oxide film of Si is rapidly removed by adding an ethanol gas to the gas system of the HF gas, and it is suggested that Si is etched with a high selectivity ratio with respect to Th-SiO ₂ and ALD-SiN. Natural oxide film.

<Other Applications of the Invention>

Further, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the apparatus of the above embodiment is merely an exemplification, and the etching method of the present invention can be carried out by means of various configurations. Further, in the above embodiment, the HF gas, the alcohol gas, or the water vapor is used as the processing gas, but the F ₂ gas may be further added. In addition, although a semiconductor wafer is used as a substrate to be processed, it is not limited to a semiconductor wafer, and may be an FPD (flat panel display) substrate or a ceramic substrate typified by a substrate for an LCD (liquid crystal display). Substrate.

5‧‧‧ etching device

40‧‧‧ chamber

42‧‧‧ mounting table

43‧‧‧ gas supply mechanism

44‧‧‧Exhaust mechanism

51‧‧‧ chamber body

51a‧‧‧ Sidewall

51b‧‧‧ bottom

52‧‧‧ 盖部

53‧‧‧ Move in and out

54‧‧‧ gate valve

55‧‧‧temperature regulator

61‧‧‧ gas introduction nozzle

62‧‧‧Common gas supply piping

63‧‧‧N ₂ gas supply source

64‧‧‧HF gas supply source

65‧‧‧Supply source of ethanol gas

66‧‧‧Gas supply piping

67‧‧‧Gas supply piping

68‧‧‧Gas supply piping

70‧‧‧Flow controller

81‧‧‧Exhaust port

82‧‧‧Exhaust piping

83‧‧‧Automatic pressure control valve

84‧‧‧vacuum pump

86a‧‧‧Capacitive pressure gauge

86b‧‧‧Capacitive pressure gauge

W‧‧‧ wafer

Claims (7)

An etching method comprising a first hafnium oxide film formed by a chemical vapor deposition method or an atomic layer deposition method on a surface thereof, and having a second hafnium oxide film (the second hafnium oxide film is adjacent to The substrate to be processed in which the first yttria film is formed of a thermal oxide film and the tantalum nitride film is disposed in a chamber, and HF gas, alcohol gas, or water vapor is supplied into the chamber, thereby The first hafnium oxide film is selectively etched by the second hafnium oxide film and the tantalum nitride film. An etching method, wherein a substrate to be processed (the substrate to be processed has a thermal oxide film and a tantalum nitride film, and a natural oxide film is formed on the surface) is disposed in the chamber to supply HF gas into the chamber The natural oxide film is selectively etched and removed with respect to the thermal oxide film and the tantalum nitride film, together with an alcohol gas or water vapor. An etching method according to claim 1 or 2, wherein the inert gas is further supplied to perform an etching treatment. The etching method according to claim 1 or 2, wherein, in the etching, the pressure in the chamber is set to be in the range of 66.7 to 1333.3 Pa, and the stage on which the substrate to be processed is placed in the chamber The temperature is set to be in the range of 0 to 30 °C. The scope of the patent or the etching method of the first 2, wherein the alcohol gas, constituted by a Department of: from ethanol (C ₂ H ₅ OH), methanol (CH ₃ OH), propanol (C ₃ H At least one selected from ₇ OH) and butanol (C ₄ H ₉ OH). The etching method according to claim 1 or 2, wherein the volume ratio of the alcohol gas or the water vapor to the total amount of the HF gas + the alcohol gas or the water vapor during the etching is 3% by volume The range of %. A memory medium that operates on a computer and memorizes a program for controlling an etching apparatus. The memory medium is characterized in that the program is executed at the time of execution, as in the first to sixth patent applications. An etching method is used to allow the computer to control the etching device.